1. Field of the Invention
The present invention relates to a clamping type lock assembly for locking a first clamped element to a second clamped element under the influence of a resilient force exerted by a latch member through which the first clamped element is engaged with the second clamped element.
2. Description of the Prior Art
In a conventional clamping type lock assembly, an operating lever has its base-end portion pivoted to a bearing plate portion of a base plate through an axle pin. The base plate is fixedly mounted on a first clamped element. A base-end portion of a latch member is pivoted to an intermediate portion of the operating lever. A receiving piece of the conventional lock assembly is fixedly mounted on a second clamped element. After a front-end portion of the latch member is engaged with the receiving piece in a condition in which the operating lever is pulled up, the operating lever is then pulled down to increase the tension of the latch member so that the first clamped element is fastened and locked to the second clamped element.
In this locked condition, a pivot point in the base-end portion of the latch member has already passed through a straight line, which connects a cross-sectional center of a front-end portion of the latch member and a cross-sectional center of the axle pin to form a boundary reference line for defining the locked condition, so that a return force due to a resilient deformation of the latch member acts on the operating lever as a torque for rotating the operating lever downward, whereby the operating lever is maintained in its locked position under the influence of such torque.
However, in the actual condition in application, for example such as in instrument boxes in railway service and the like, the operating lever is subjected to severe vibrations through the clamped elements, and, therefore floats off from a front surface of the clamped elements, which often permits the pivot point of the base-end portion of the latch member to pass through the above boundary reference line so as to further separate from the clamped elements, i.e., to unlock the lock assembly.